The present invention relates to an improved magnetic medium particularly adapted for use with rotating head magnetic recorders, also referred to as "transverse" magnetic recorders.
Rotating head recorders have been used for the last several years for recording video or television signals. Such signals are analog in character which permits repeated signal usage to compensate for defective recording, while not materially detracting from the quality of the television picture presented on a television set or CRT screen.
Such video recorders employ carrier recording techniques with the carrier at the upper portion of the frequency band of the signals being recorded. Such video recorders have been employed for digital data recording by modulating digital data signals on the normal video carrier. In contradistinction, most other digital data recorders employ baseband recording rather than heterodyne the information-bearing signals on a carrier.
Another aspect of digital data signal recording is that any error conditions cannot be obviated in the same manner as video recording signals can submerge or enable errors to be ignored. In data recording, all signals read back from a record medium must be correct. Further, tape motions employed with digital signal recorders and that of video recorders are quite different. Requirements of a digital signal record medium usually require that the magnetic recorder should be able to step the medium to any selected position along its longitudinal length and then precisely indicate to controlling apparatus that the medium is at the desired location. In one form of digital signal data recorders employing rotating heads, during the recording, the magnetic medium is completely stopped; i.e., the apparatus operates on a step-by-step or incremental mode. That is, one record stripe is recorded while the tape is stopped. The tape moves to the next stripe with additional data being recorded, etc. Accordingly, any article to be employed with digital data recorders should be capable of being operated efficiently in a step-by-step or incremental mode, as well as in a continuous motion or slewing mode.
The history of digital data recording on magnetic tape media indicates that as the technology advances there is a great desire on the part of users that there be backward compatibility. The term "backward compatibility" means that all newly designed digital data recorders have a capability of reading all previous digital data formats. For example, in the 1/2 inch tape area, digital data recorders employing 1,600 cpi phase-encoded recording also usually have the capability of reading the prior 800, 556, and 200 cpi NRZI recording. Accordingly, any improved article for use with rotating head digital data recorders should facilitate this so-called backward compatibility.